An ex-situ two-step strategy coupling catalytic pyrolysis with chemical fixation for the deep dechlorination and aromatization of polyvinyl chloride (PVC)

The accumulation of polyvinyl chloride (PVC) waste poses a critical environmental challenge due to its high chlorine content and the release of hazardous byproducts during conventional thermal treatment. Developing a robust, chlorine-tolerant technology for converting PVC into high-value chemicals is therefore essential for the circular economy. Herein, we propose a sustainable “catalytic pyrolysis–adsorption” decoupling strategy that integrates hydrocarbon recovery with efficient chlorine fixation. By utilizing an ex-situ configuration in a tandem fixed-bed reactor comprising Fe/Co-modified ZSM-5 catalysts and a CaO adsorbent, this process achieves the synergistic transformation of waste PVC and mixed plastics into clean aromatic hydrocarbons. Mechanistic investigations reveal that the spatial separation of pyrolysis and adsorption allows for precise reaction control: the modified zeolite promotes dehydroaromatization, while CaO chemically sequesters gaseous HCl as thermally stable CaCl 2 , effectively blocking the reformation of organochlorides. Under optimized ex-situ conditions, the system achieves a maximum liquid oil yield of 19.71 wt% for pure PVC and 23.73 wt% for simulated mixed plastics, with the final chlorine content in the liquid oil dramatically reduced to 5.02 mg/L. Furthermore, the selectivity toward high-value monocyclic aromatic hydrocarbons (BTEX) in the oil phase is significantly enhanced via bimetallic-driven dehydroaromatization, offering a robust pathway compliant with clean fuel standards. This work provides a green, scalable pathway for the detoxification and valorization of chlorine-rich plastic waste, offering a promising solution to the “chlorine bottleneck” in plastic recycling.